In fuses for elevated circuit voltages it is often necessary to use fusible element means whose length exceeds that of the casing, or fuse tube. In such instances the fusible element or elements are generally wound helically around a support of electric insulating material. Some such supports are made of a ceramic material and are substantially star-shaped in cross-section. Other such supports are made up of a plurality of elongated plate means of electric insulating material having radially outer longitudinal edges supporting the fusible element means, and having transverse edges engaging radially extending grooves provided in the axially inner end surfaces of plug terminals closing the ends of the casing, or fuse tube.
The dimensional stability of a fuse of the latter kind depends largely upon the strength of the means by which the supporting plates for the fusible element means are held in the plate receiving grooves of the plug terminals. Clamping of the portions of the fusible element supporting plates inside of plate-edge-receiving grooves of plug terminals is not satisfactory because even if the friction between the plates and the plate-receiving-grooves is initially large, and the structure initially dimensionally stable at room temperatures, the grip of the side walls of the grooves is drastically reduced and the dimensional stability of the structure impaired when the width of the grooves increases as the temperature of the plug terminals increases when the fuse is carrying current.
Another way of affixing the constituent plates of fusible element supports in grooves of plug terminals is by resorting to the use of adhesive bonds. Such bonds provide structures which have the required dimensional stability, but are relatively difficult to establish and may involve the use of adhesives which are dangerous to the health of unskilled labor.
Other relatively complex solutions to the above problem are found in U.S. Pat. Nos. 3,846,728 to E. Salzer, 12/05/74 for HIGH-VOLTAGE FUSE INCLUDING INSULATING MANDREL FOR SUPPORTING FUSIBLE ELEMENTS and in U.S. Pat. 3,851,289 to F. J. Kozacka, 12/26/74 for HIGH-VOLTAGE FUSE HAVING HELICALLY WOUND FUSIBLE ELEMENT AND SUPPORT FOR HELICALLY WOUND FUSIBLE ELEMENT.
It is the prime object of the invention to provide electric fuses of the above description not subject to the limitations of similar prior art devices.